3.
Noise IMPACT
Introduction
3.1
This section presents potential
noise impacts associated with the construction and operation phases of the
Project. Helicopter noise during the operation phase would
be a key issue in the study. Noise
sensitive receivers (NSRs) in the vicinity of the site were identified. The
potential noise impacts on the NSRs were predicted and mitigation
measures considered
and proposed.
3.2
The
assessment criteria, noise metric and methodology in assessing the noise impact
arising from the operation of the Project were proposed and approval obtained
from EPD, in accordance with the EIA Study Brief.
Environmental Legislation and Standards
Construction Phase
3.3
Noise impacts were assessed in
accordance with the criteria and methodology given in the Technical Memoranda
made under the Noise Control Ordinance (NCO) and EIAO-TM.
3.4
The NCO provides the statutory
framework for noise control. This
defines statutory limits applicable to equipment used during the construction
phase of the proposed works in the study area.
The NCO invokes three Technical Memoranda, which define the technical
means for construction noise assessment:
·
Technical Memorandum
on Noise from Construction Work in Designated Areas (DA-TM);
·
Technical Memorandum
on Noise from Construction Work other than Percussive Piling (GW-TM); and
·
Technical Memorandum
on Noise from Percussive Piling (PP-TM).
3.5
The NCO and the accompanying
Technical Memoranda provide a mechanism for assessing noise levels and the
statutory power to control noise.
3.6
Under the GW-TM, noise from
construction activity is not restricted during the period 0700 - 1900 hours on
weekdays, except public holidays. However, the EIAO-TM identifies a daytime
general construction noise limit of 75 dB(A) Leq (30 minutes) for
domestic premises, 70 dB(A) Leq (30 minutes) for educational
institutes and places where unaided voice communication is required and 65dB(A)
Leq (30 minutes) is allowed for school during examination period.
This standard was used as assessment criteria in the construction noise
assessment.
3.7
If construction activities are
required to be carried out between 1900 and 0700 hours and all day on Sundays
and public holidays, activities involving the use of powered mechanical
equipment (PME) for construction work are prohibited unless a construction
noise permit (CNP) has been obtained.
The Noise Control Authority would consider a well-justified CNP
application, once filed, for construction works within restricted hours as
guided by the relevant technical memorandum issued under the NCO. The Noise Control Authority would take into
account of contemporary conditions / situations of adjoining land uses and any
previous complaints against construction activities at the site before making
the decision to grant a CNP. Nothing in
this EIA Report shall bind the Noise Control Authority in making its
decision. If a CNP is to be issued, the
Noise Control Authority shall include in the permit any condition he thinks
fit. Failure to comply with any such
conditions would lead to cancellation of the CNP and prosecution action under
the NCO. A CNP could be granted
provided that the Acceptable Noise Level (ANL) for the NSRs could be complied
with. ANLs are assigned depending upon
the ASR. The corresponding basic noise
levels (BNLs) for evening and nighttime periods, together with a daytime
standard, are given in Table 3.1.
Table 3.1 Construction
Noise Criteria for Activity other than Percussive Piling
|
Time Period
|
Basic Noise Level (BNLs) (dB(A))
|
|
ASR A
|
ASR B
|
ASR C
|
|
Evening (1900 to 2300 hours) (1)
|
60
|
65
|
70
|
|
Night (2300 to 0700 hours)
|
45
|
50
|
55
|
Notes: (1)
includes Sundays and Public Holidays during daytime and evening
(2) ASR – Area Sensitivity Rating
3.8
If percussive piling is required
for the Project in future, the Contractor shall obtain a valid CNP before
undertaking.
Operation Phase
3.9
The Cap. 312 Civil Aviation (Aircraft Noise) Ordinance has provisions
for helicopter noise control, as extracted below:
(1) If the Director
considers it appropriate, for the purpose of avoiding, limiting or mitigating
the effect of noise and vibration connected with the taking off or landing of
aircraft at an aerodrome, to prohibit aircraft from taking off or landing, or
to limit the number of occasions on which they may take off or land, at an
aerodrome during certain periods, he may by notice in the Gazette-
(a) prohibit aircraft of
descriptions specified in the notice from taking off or landing at the
aerodrome (otherwise than in an emergency) during periods so specified;
(b)
specify the maximum number of occasions on which aircraft of
descriptions so specified may be permitted to take off or land at the aerodrome
(otherwise than in an emergency) during periods so specified; or
(c) determine the persons who
shall be entitled to arrange for aircraft of which they are the operators to
take off or land at the aerodrome during the periods specified under paragraph
(b) and, in respect of each of those persons, the number of occasions on which
aircraft of a particular description of which he is the operator may take off
or land at the aerodrome during those periods.
(Section:
6, Heading: Restrictions on landing and take off, Version Date: 30/06/1997)
3.10
The NCO does not have control
over helicopter noise. Under the EIAO, “a new helipad within
300m of existing or planned residential development” is a Designated Project
under Schedule 2, Part I (B2) and requires an environmental permit under the
EIAO for its implementation.
Daytime (0700 – 1900 hours)
3.11
With regard to the assessment of
operational helicopter noise impacts, the EIAO-TM designates acceptable noise
levels based on the land uses at the NSRs.
Table 3.2 summarises the
noise standards for daytime.
Table 3.2 Standards for Helicopter Noise (0700 to 1900 Hours)
|
Common Uses
|
Helicopter Noise Lmax dB(A)
0700 to 1900 Hours
|
|
All domestic premises including temporary housing
accommodation
|
85
|
|
Hotel and hostels
|
85
|
|
Offices
|
90
|
|
Educational institutional
including kindergartens, nurseries and all others where unaided voice
communication is required
|
85
|
|
Places of public Worship and courts of law
|
85
|
|
Hospital, clinics, convalescences and homes for the aged,
diagnostic rooms, wards
|
85
|
Note: (1) The above standards apply to uses that
rely on opened windows for ventilation.
(2)
The above standards shall be viewed as the maximum permissible noise levels
assessed at 1m from the external façade.
Evening Time (1900 – 2300 hours) &
Night Time (2300 – 0700 hours)
3.12
With reference to the EIAO-TM,
there are currently no specified evening time and night time assessment
criteria for helicopter noise, and such criteria should be determined on a case
by case basis.
International Review
3.13
Therefore a literature review was
conducted for the reference of this EIA study on the standards or criteria
adopted in overseas countries for helicopter noise assessment (as detailed in Appendix 3.1). With reference to overseas
helicopter/aircraft studies, Ldn or Day-Night Average Sound Level
(DNL) is commonly used as noise metric for helicopter noise criteria in Europe
and North America. DNL is a cumulative
noise measure based on an average of all the sounds occurring during a typical
24-hour period. DNL due to a particular
sound source such as helicopter can be calculated from measurements or
estimates of the sound exposure levels (SEL) of individual operations if the
number and time of such operations during a 24-hour period are known. The helicopter noise criteria established by
the Federal Aviation Administration (FAA) also adopt DNL for determining
compatible land uses in and around the vicinity of heliports.
3.14
In general, the DNL adopted in
overseas countries as helicopter noise criteria ranges from 50 – 65 dB(A),
depending on site background noise levels.
More stringent noise criteria (lower than 60 dB(A)) are commonly applied
to rural environment and residential areas, while higher noise criteria, DNL 60
– 65 dB(A), are applied to urban areas with high density of commercial
buildings and major transport routes (such as Boston, San Francisco and
Washington which are similar to present site).
A weighting factor, a 10 dB(A) penalty would be added to the noise
criteria for late night time hours (usually defined as the hours from 2200 –
0700 hours) to compensate for sleep interference and other disruptions.
3.15
According to the published
criteria under 14 Code of Federal Regulations by the FAA, 65 DNL dB is the
threshold of significance for determining compatible land uses i.e. noise
levels predicted at residential land uses more than 65 DNL is considered incompatible. This criterion, 65 DNL dB is also adopted
in the United State Department of Transport (DOT), Untied State Department of
Housing and Urban Development (HUD) and United State Environmental Protection
Agency (USEPA).
3.16
Other than DNL, equivalent sound
level (Leq) over a specified period is also a common helicopter noise criteria
adopted in overseas countries. Leq is
an average of all the sounds occurring during a specified period, but without
any weighting factors for time periods.
A range of 57 – 72 dB(A) has been applied to urban areas overseas (e.g.
California).
Assessment Criteria for this EIA Study
3.17
The operation hours of the
proposed new helipad is the same as the existing helipad between 0800 to 2259
hours.
3.18
The proposed new heliport is a
Designated Project under Schedule 2 of the EIAO and therefore the specified day
time Lmax assessment criteria in the EIAO-TM should be followed. Other assessment criteria are proposed as
appropriate for this EIA Study, with reference to the international review and
the Project’s specific site condition.
3.19
It should be noted that the
existing MFT Helipad is an Exempted Designated Project and not governed by the
EIAO.
Daytime (0700 – 1900 hours)
3.20
The Lmax 85 dB(A) helicopter
noise criteria during 0700 – 1900 as stipulated in the EIAO-TM should be applied to the
daytime helicopter operation at the proposed new helipad.
Evening Time (1900 – 2300 hours)
3.21
With
reference to the helicopter
noise criteria of overseas countries, DNL is used as helicopter noise criteria
for a whole day. However, the use of
DNL as assessment criteria for the evening time would not be
applicable in this case as DNL is based on the sound energy averaged over 24 hours. There would be no helicopter operation at
the proposed new helipad during night time period (after 2300 hours). Instead,
Leq over a specified period would be more appropriate as the assessment criteria
to cover the evening operational period for this EIA study. As the operation of helicopters at the proposed new
helipad would not be later than 2300 hrs, it is recommended to adopt Leq (4
hours) as a noise metric for evening time helicopter noise limit for this
study.
3.22
For references in establishing an
appropriate Leq as evening time assessment criteria, helicopter noise surveys
were conducted in January, March and April 2005 to collect data of the existing
noise levels in the study area.
Measurements were conducted on representative locations
and based on worst case scenarios of the existing helicopters which are near
the end of their life-cycle and noisier.
Based on the measurement data as detailed in Appendix 3.5 and the present flight frequency (refer to Table 3.6), the noise levels Leq (4
hours) during 1900 – 2300 hours at the closest NSRs including the Bauhinia, Ka
On Building and Talon Tower were estimated.
Details results refer to Appendix
3.7. Results indicated that the
noise levels, Leq (4 hours) at these noise receivers ranged from 63 – 68 dB(A)
during 1900 – 2300 hours based on different approach directions (east or west
depending on wind directions) and the present flight frequency (16 movements
during 1900 – 2300 hours). If the
existing MFT helipad is operated at the existing allowable flight frequency (22
movements during 1900 – 2300 hours), a maximum of noise level of up to Leq (4
hours) 69 dB(A) during 1900 – 2300 hours was estimated at the NSRs.
3.23
The proposed expansion of
heliport facilities at the MFT assessed in this EIA study is located in the
urban Sheung Wan/Central area. The
study area within a 300m radius consists of high density, diversed developments
including many large commercial/retail centres, highways and transport
interchanges and several residential buildings. The dominant noise sources of the study area are contributed from
a number of heavily
trafficked roads including Connaught Road Central and Queen’s Road
Central. The noise surveys on-site
indicated a high background noise levels of Leq (4 hours) 70-73 dB(A).
3.24
Reviewing the site condition in
the study area, the noisy environment (major commercial areas and busy road
traffic) would be similar to modern city in foreign countries such as Boston,
San Francisco and Washington. In addition with reference to the foreign noise
research studies and Federal agencies, 65 dB(A) noise levels were often adopted
as certain guidelines for residential land uses and environmental sound
levels. Therefore, it is proposed to
adopt a noise assessment criterion of Leq(4hours) 65 dB(A) during 1900 – 2300
hours for the proposed new helipad in the evening time helicopter noise
assessment of the present EIA Study.
3.25
The recommended evening time
assessment criterion of Leq (4 hours) 65 dB(A) is applied to the sensitive uses
(as defined in the EIAO-TM) which rely on openable windows for
ventilation. It should be noted that
this proposed noise assessment criterion is specifically established for the
present EIA study of this Project, taking into account the local
existing noise environment of the study area and therefore should not be
applied to other helicopter related projects in future.
3.26
As Leq(4 hours) is an average of
all the sounds occurring during 4-hour period, it cannot fully reflect the
single event during that period. It is
also recommended to include additional assessment criterion, Lmax 85 dB(A) for
residential uses during 1900 – 2300 hours.
Description of the Environment
3.27
The MFT Building is located at
the seafront of Sheung Wan which is an urban area with high density of
commercial buildings. The major
existing noise source is traffic noise from the heavily trafficked Connaught
Road, engine noise from Turbo Jet and helicopter noise from the existing
helipad at MFT Building (also see Section 3.23 above).
Assessment Area & Noise Sensitive Receivers
Construction Phase
3.28
The assessment area for construction
noise in the EIA Study will include all areas within 300m from the site
boundary. The nearest NSRs identified
include the Bauhinia and Ka On Building.
It is expected that Shun Tak Centre would provide partial screening
effect on these two NSRs, Figure 3.6
shows the screening effect from the Shun Tak Centre on the NSRs.
Operation Phase
3.29
The assessment area for
helicopter noise in the EIA Study will be the area within 300m from the project
boundary and flight paths for the MFT Heliport within the Victoria Harbour
area.
3.30
Representative NSRs within the
study area are identified in accordance with the requirement as mentioned in
Section 3.4.1 of the EIA Study Brief and Annex 13 of the EIAO-TM, and the
latest Outline Zoning Plans (Central District OZP (S/H4/12) dated 18 February
2003, Sai Ying Pun & Sheung Wan OZP (S/H3/20) dated 16 December 2003 and
Kennedy Town & Mount Davis OZP (S/H1/14) dated 2 November 2004). The selected representative noise sensitive
receivers are affected by helicopter noise as they are located nearest to the
helipad and helicopter flight path for MFT heliport. If the NSRs, e.g. commercial buildings, are provided with central
air-conditioning and do not rely on openable windows for ventilation, no
adverse helicopter noise impacts would be expected on these sensitive receivers
and therefore they would not be considered in the assessment. In addition, some locations including
affected parties along Shing Sai Road, New Praya Kennedy Town and Victoria Road
(up to the boundary of the Central and Western District Constituency) and large
residential estates which are adjacent to and along the flight paths to and
from the MFT Heliport, are also identified.
3.31
As the helicopter would not fly
eastward of the proposed new helipad (except during approach or take off), and
the NSRs at the east of the helipad are provided with central air-conditioning
and do not rely on openable window for ventilation, no significant helicopter
noise impacts would be expected at these NSRs and therefore they are not
included in the assessment. Detailed
information of representative NSRs are summarised in Table 3.3 and the locations are illustrated in Figure 3.1.
3.32
The assessment area would be
reduced accordingly if the first layer of noise sensitive receivers, closer
than 300m from the project boundary, provides acoustic shielding to those
receivers located further away. Figures 3.2 – 3.4 show the
cross-sections to illustrate the acoustic shielding effect from first layer of
NSRs to the second and third layer of sensitive receivers. A view from the existing helipad at the MFT
Building to the sensitive receivers and views from representative sensitive
receivers/building next to representative receivers are attached in Appendix 3.2.
Table 3.3 Locations of Representative
Noise Sensitive Receivers
|
NSR ID
|
Locations
|
Land Use
|
No. of Floors
|
Justification for selection
|
|
N1
|
Queen’s Terrace
|
Residential
|
55
|
The highest building comparing
with the nearby NSRs.
|
|
N2
|
Hongway Garden
|
Residential
|
35
|
One of NSRs nearest to the helipad
and has line of sight of the site.
Building height is higher comparing with nearby NSRs (5 – 10 storeys).
|
|
N3
|
Harmony Court
|
Residential
|
25
|
One of NSRs nearest to the
helipad and has line of sight of the site.
Building height is higher comparing with nearby NSRs.
|
|
N4
|
Shun Loong Mansion
|
Residential
|
22
|
The highest building comparing
with the nearby NSRs.
|
|
N5
|
The Bauhinia (Korea Centre)
|
Residential
/Commercial
|
13
|
One of the nearest NSRs to the
helipad.
|
|
N6
|
Ka On Building
|
Residential
|
18
|
One of the nearest NSRs to the
helipad.
|
|
N6a
|
Talon Tower
|
Residential
|
20
|
The first layer of NSRs to the
helipad.
|
|
N7
|
Sea View Mansion
|
Residential
|
23
|
The first layer of NSRs to the
helipad and its height is higher comparing with nearby NSRs.
|
|
N8
|
Po Fung Building
|
Residential
|
22
|
The highest building comparing
with the nearby NSRs.
|
|
N9
|
Connaught Garden
|
Residential
|
30
|
The first layer of NSRs to the
helipad and its height is higher comparing with nearby NSRs.
|
|
N10
|
Kwan Yick Building Phase III
|
Residential
|
24
|
The first layer of NSRs to the
flight route and its height is higher comparing with nearby NSRs.
|
|
N11
|
Cheung Ling Mansion
|
Residential
|
22
|
The first layer of NSRs to the
flight route and its height is higher comparing with nearby NSRs.
|
|
N12
|
Kwan Yick Building Phase II
|
Residential
|
20
|
The first layer of NSRs to the
flight route and its height is higher comparing with nearby NSRs.
|
|
N13
|
Kong Chian Tower
|
Residential
|
23
|
The first layer of NSRs to the
flight route.
|
|
N14
|
Kwan Yick Building Phase I
|
Residential
|
22
|
The first layer of NSRs to the
flight route. The building heights of
nearby NSRs are similar levels and they have same angle of view to the flight
route.
|
|
N15
|
Yip Cheong Building
|
Residential
|
15
|
|
N16
|
The Belcher’s
|
Residential
|
48
|
The highest building comparing
with nearby NSRs.
|
|
N17
|
Bic Wah Court
|
Residential
|
21
|
The first layer of NSRs with
direct line of sight to flight route without any screening.
|
|
N18
|
Kennedy Town Centre
|
Residential
|
34
|
The first layer of NSRs with
direct line of sight to flight route without any screening.
|
|
N19
|
Manhattan Heights
|
Residential
|
48
|
The first layer of NSRs with
direct line of sight to flight route without any screening. The building height is the highest
comparing with nearby NSRs, e.g. The Merton (Planned NSRs).
|
|
N20
|
Centenary Mansion
|
Residential
|
40
|
The first layer of NSRs with
direct line of sight to flight route.
The building height is the highest comparing with nearby NSRs
|
|
N21
|
Cayman Rise
|
Residential
|
31
|
Highest building comparing with
nearby NSRs.
|
|
N22
|
Hong Kong Institute of Vocation
Education (Morrison Hill) Kennedy Town Centre
|
School
|
6
|
NSR located at a higher
platform.
|
|
N23
|
Kung Man Village
|
Residential
|
3
|
NSR located at a higher
platform.
|
|
N24
|
Serene Court
|
Residential
|
29
|
Highest building comparing with
nearby NSRs and direct line of sight to flight route.
|
|
N25
|
Chee Sing Kok Social Centre of
the Humanity Life and Staff Quarter
|
Social Centre and Residential
|
3
|
NSR located at a higher
platform.
|
Note:
Estimated number of total flats for the above noise sensitive receivers is
about 4,500
3.33
In accordance with the site
condition, the nearest NSRs including The Bauhinia, Ka On Building and Talon
Tower, would be affected by all modes (Approach, Hovering, Idling and Take Off)
of helicopter operations at the proposed new helipad as they are located within
500m from the proposed new helipad and are expected to be the worst affected
NSRs during the operation of helicopter at the proposed new helipad. Other NSRs which are identified in Table 3.3, would be expected to be
affected by the helicopter passing by only as they are located far away from
the proposed new helipad (at least 500m away) or they are the second or third
layer of the NSRs which would be noise protected from the first layer of high
rise buildings during operation of helicopter at the proposed new helipad. In order to evaluate the impact from
helicopter passing by, other than the above identified three NSRs, Hongway
Garden (N2), Harmony Court (N3) and Sea View Mansion (N7), would be the nearest
NSRs to the flight path and are selected for quantitative assessment. Table
3.4 summarises the six selected assessment points that represent all the identified
NSRs for carrying out quantitative noise assessment in the EIA Study. If no noise exceedance of daytime noise
criterion and proposed evening time noise criteria is found for these six
assessment points, other NSRs as identified in Table 3.3 would also comply with
the criteria.
Table 3.4 Summary
of Assessment Points
|
NSR ID
|
Locations
|
Land Use
|
No. of Floors
|
Mode of helicopter operation to be assessed
|
|
N2
|
Hongway Garden
|
Residential
|
35
|
Passing by
|
|
N3
|
Harmony Court
|
Residential
|
25
|
Passing by
|
|
N5
|
The Bauhinia
|
Residential
/Commercial
|
13
|
Approach, Hovering, Idling and
Take Off
|
|
N6
|
Ka On Building
|
Residential
|
18
|
Approach, Hovering, Idling and
Take Off
|
|
N6a
|
Talon Tower
|
Residential
|
20
|
Approach, Hovering, Idling and
Take Off
|
|
N7
|
Sea View Mansion
|
Residential
|
23
|
Passing By
|
Identification of Potential Impact
Construction Phase
3.34
The proposed new helipad would be
built on the roof-top of
the existing Inner Pier at the MFT. There would not be any demolition of
existing structures for the helipad expansion works, and site formation or
earthworks would not be required for the Project. The only construction activity for the Project which could be a
potential source of construction noise would be:
·
Piling
for support the steel framework structure for proposed new helipad;
·
Reinforcement
works for the proposed new helipad and the minor expansion of existing helipad.
3.35
In view of the limited scale of
the project works and screening effect from Shun Tak Centre, significant
construction noise impact on the nearest NSRs, would not be expected.
3.36
The construction activities would
be undertaken during non-restricted hours based on the existing construction
programme. If the Contractor would
carry out the construction activities during restricted hours if required in
future, the Contractor shall apply the CNP from the Noise Control Authority for
activities involving the use of powered mechanical equipment (PME).
Operation Phase
3.37
Helicopter noise from the
operation of the proposed Project would be a key concern to the NSRs in
vicinity of the site, comprising cumulative impacts from the existing helipad
and new helipad at MFT. The Sheung Wan Domestic Heliport project was
suspended, and therefore no potential cumulative helicopter noise impact is
anticipated from other existing/potential helicopter operations in the vicinity
of the study area of the Project.
Assessment Methodology
Construction Phase
3.38
The construction works for the
expanded heliport are tentatively estimated to commence in mid 2006 for
completion in end 2007. The
construction would comprise construction of the heliport with a tentative
duration of 18 months.
3.39
The methodology outline in the
GW-TM has been used for the assessment of construction noise. Powered Mechanical Equipment (PMEs) used for
the different construction tasks opined by the engineer is presented in Table 3.5. It was assumed that the on-time operated for all PMEs would be
100%. The plant inventory has been
confirmed by the proponent as being practicable for completing the works within
the schedule timeframe.
Table 3.5 Powered Mechanical Equipments Used
During Construction Phase
|
Powered Mechanical
Equipment
|
Reference
|
No. of Plant
|
Sound Power Level
dB(A)
|
|
Crane, tower (electric)
|
CNP 049
|
1
|
95
|
|
Derrick Barge
|
CNP 061
|
1
|
104
|
|
Generator
|
CNP 102
|
1
|
100
|
|
Air Compressor
|
CNP 002
|
1
|
102
|
|
Breaker, hand-held
|
CNP 026
|
1
|
114
|
|
Concrete mixer (electric)
|
CNP 045
|
1
|
96
|
|
Concrete Pump
|
CNP 047
|
1
|
109
|
|
Poker, vibratory, hand-held
|
CNP 170
|
1
|
113
|
|
Welding Set
|
1
|
2
|
78
|
Note:
1 – According to the information from Spur Line EIA Report
3.40
It was assumed that all PMEs
required for a particular construction activity were located at the notional or
probable source position of the segment where such activity was performed. The assessment was based on the cumulative
SWL of PME likely to be used for each location, taking into account the
construction period in vicinity of the receiver location. As a worst case scenario, the PMEs of each
construction phase were assumed to be operated concurrently at any given
time. The sound pressure level of each
construction phase was calculated, depending on the number of plant, their
on-time percentage of operation and their distance from receivers. A positive 3 dB(A) façade correction was
added to the predicted noise levels in order to account for the façade effect
at the NSR.
3.41
There is no other project to be
constructed concurrently within the study area of this Project.
Operation Phase
Type
of Helicopters
3.42
In accordance with the
information provided by CAD, potential helicopter types that would be used at
MFT Heliport include:
·
Sikorsky S76C+, currently in use
at the existing MFT helipad;
·
Sikorsky S92, potentially be used
at the proposed new helipad at MFT upon expansion;
·
Aerospatiale AS355N Ecureuil
(Twin Squirrel); potentially be used at the proposed new helipad at MFT upon
expansion; and
·
Bell AB139, potentially be used
at the proposed new helipad at MFT upon expansion
3.43
Apart from Sikorsky S92 and Bell
AB139, the other two types of helicopters have been operated in Hong Kong. In accordance with the manufacturer’s noise
data and the measurement data, the noise level arising from Sikorsky S76C+ is
higher than Twin Squirrel and Bell AB139 in all modes of helicopter operation
(Refer to Appendix 3.3). Helicopter noise impact assessment would
therefore focus on the operation of Sikorsky S76C+ at the existing/proposed new
helipad and Sikorsky S92 at the proposed new helipad as a worst case scenario
in the EIA study. Due to the limited
size of existing helipad, Sikorsky S92 cannot land on the existing helipad at
MFT Building.
Frequency of Services and Time of
Operation
3.44
The maximum capacity of each
helipad at MFT would provide 8 movements per hour. Therefore, the maximum capacity for the two helipads upon
expansion would be 16 movements per hour during 0800 – 1800 hrs in the
future. According to the Local Traffic Regulations
of Aeronautical Information Publication – Hong Kong (AIP), the current
restrictions on the existing MFT Helipad are as follows:
§
The allowable operation period is
between 08:00 and 22:59 everyday
§
No more than 3 landings & 3
take-offs per hour between 18:01 & 22:59
§
No more than 14 landings & 14
take-offs between 18:01 & 22:59
§
No flight after 23:00
3.45
It is assumed that the operation
hours of the MFT heliport
upon expansion will remain as 0800 to 2259
hours everyday in future. As required
in the EIA study brief, the existing helipad and proposed new helipad operating
at the maximum allowable operation period and capacity to meet traffic demand
in future would be used as a worst case scenario in the assessment. Table
3.6 presents the current and future operation mode of the existing MFT
helipad and proposed new helipad.
Table 3.6 Current and Future Operation Mode of
the Existing MFT Helipad and Proposed new helipad
|
Item
|
Current Operation
Mode(1)
(Existing Actual
Condition)
|
Current Operation
Mode
(Allowable
Condition)
|
Future Operation
Mode (2)
|
|
Flight
frequency
|
Time: 0900-19:00
Existing Helipad – 38 movements
|
Time: 0800-1900
Existing Helipad – 86 movements
(design capacity)
|
Time: 0800-19:00
Existing Helipad – 86
movements (design capacity)
Proposed New Helipad – 86 movements
(design capacity)
|
|
Time:
19:01 – 22:59
Existing
Helipad - 16 movements
|
Time
19:01 – 22:59
Existing
Helipad – 22 movements
|
Time:
19:01 – 22:59
Existing
Helipad + Proposed New Helipad – maximum 34 movements.
Details
refer to Appendix 3.9
|
|
Type
of Helicopter
|
Sikorsky
S76C+
|
Sikorsky
S76C+
|
Potential
helicopter types: Sikorsky S76C+, Sikorsky S92, Aerospatiale AS355N Ecureuil
(Twin Squirrel), Bell AB139, etc.
|
Note: (1) Based on the frequency of helicopter movements obtained from the
existing helicopter
operator at MFT Helipad.
(2)
As a worst case scenario, the operation hours are from 0800 – 2259 and maximum capacity of 8 movement per
hour per helipad are assumed.
Flight
Path
3.46
According to the information
provided by CAD, the most commonly used separation standards are vertical separation,
1000 feet between 2 aircraft or geographical separation. There is not a finite horizontal separation
distance between 2 helicopters.
However, as advised by CAD, a helicopter operating west of Macau Ferry
Pier is separated from another helicopter operating east of North Point. For the same direction of flight, if two
helicopters are both tracking westbound over the harbour, the one from North
Point (following the other helicopter) can be cleared to Wan Chai Ferry Pier
when the other helicopter has passed Macau Ferry Pier. It is considered that the minimum distance
between two helicopters during flying as quoted in the above case would be
approximately 2km and serves as a reference.
3.47
According to the requirement of
International Civil Aviation Organization (ICAO), the airspace around heliports
is required to be maintained free from obstacles so as to permit the intended
helicopter operations at the heliport to be conducted safely. The minimum angles between the approach and
takeoff routes should be at least 150 degrees.
The indicative flight paths from/to the proposed new helipad at MFT,
which fulfil the required requirements and pose the minimum noise impact to the
surrounding environment, are presented in Figure
3.5.
Helicopter
Noise Emission Data
3.48
The noise emissions from the
helicopter will be different depending on different helicopter types and modes
of operation, including approach, hovering, idling on the ground and departure
from the helipads. The certification
noise data for helicopter S76C+ is attached in Appendix 3.3. Noise
measurements for helicopters S76C+ operated at existing MFT helipad were also
conducted so as to obtain the noise emission data (Leq and Lmax) at the actual
site condition in terms of number of passengers carried in the
helicopters. A conservation assumption
has been adopted as the measured existing S76C+ helicopters are at an old stage
and noisier. The measurement methodology is presented in Appendix 3.4.
3.49
Helicopter noise surveys were
conducted on 15 & 27 January 2005, 23 March 2005 and 4 April 2005. The noise levels, Lmax and Leq, at the
representative sampling locations were measured during different modes
(including Approach, Hovering, Idling and Takeoff) of helicopter S76C+
operation. The measurement results and
the flight details at MFT are summarised in Appendix 3.5. Comparing
with the certification noise data and survey data, measured noise levels were
higher, and were therefore adopted for assessment in the EIA Study as a
conservative approach. The noise
levels predicted at the NSRs due to helicopter passing-by was determined based
on the certification noise data.
3.50
The above
measurement data for S76C+ were not measured under a full-load condition in
terms of number of passengers carried in the helicopters. To be conservative, adjustments to the
measured noise levels need to be made for full load condition in the noise
prediction. The number of passengers
for each movement of S76C+ during measurement is provided by CAD. The weighting adjustment would make
reference to “Consultancy Study on Helicopter Traffic Demand and Heliport
Development in Hong Kong”. The
correction factor for adjusting to full-load condition was based on the
following equation:
Correction
for full loading, dB(A) = 10 x log (Wf / Wi)
where Wf refers to gross weight under full loading
condition
Wi refers to gross weight during
measurement
3.51
Maximum capacity of S76C+ is 12
passengers and a pilot. The gross weight of S76C+ under empty condition is 3731
kg. Assuming the weight of each
passenger is 70 kg, the additional sound pressure levels for helicopter S76C+
are as follows:
Table 3.7 Adjusted Helicopter Noise Level for
S76C+ under Full-Load Condition
|
Operation Mode
|
Gross Weight under
Empty Condition, kg
|
Adjusted Gross Weight
under Full Load Condition, kg
|
|
S76C+
|
3731
|
4641
|
3.52
Except the weighting adjustment,
background noise levels were also excluded in the measured noise level before
adoption for calculation.
3.53
The noise levels at the
representative NSRs due to helicopter S76C+ / S92 flying along the flight path
were calculated based on certification noise data, with the full loading
weighting adjustment.
3.54
As the helicopter type of S92 is
not on the market yet, it is therefore not possible to conduct on-site
measurement to obtain the noise emission data.
According to the information provided by the helicopter manufacturer in
February 2004, they conducted a study for comparison of measurement noise data
for helicopter S92 and S76C+ during Approach and Takeoff. Results indicated that the Lmax of S92 was
2.9 dB(A) higher than S76C+ during Approach mode of operation; while the
difference in Lmax between S92 and S76C+ during Takeoff mode of operation was
not more than 0.1 dB(A). The detail
information is attached in Appendix 3.3. As a conservative approach, the noise levels
at the selected NSRs due to operation of helicopter S92 were estimated based on
the corrected noise levels of S76C+ at these NSRs with full loading and the
noise difference between the S76C+ and S92 from the manufacturer’s information,
rather than make reference to the certification data (refer to Appendix 3.3).
3.55
To determine the noise impacts
arising from the operation of helicopter S92 at the representative NSRs during
evening hours (1900 – 2259), the Leq at the representative NSRs would be
calculated based on the measured Leq of S76C+ (with full loading correction)
and the noise difference between the helicopter S76C+ and S92 from the
manufacturer’s information.
Assessment Scenarios
3.56
The daytime and evening time
helicopter noise impact due to current operation mode of the existing MFT
helipad and future operation mode of proposed new helipad, as well as the
cumulative noise impact from existing helipad and proposed new helipad at MFT
Building were assessed. As the project
for Sheung Wan Helipad is suspended, there is no potential cumulative daytime
and nighttime helicopter noise impacts from other existing/potential helicopter
operations in the vicinity of the Project
3.57
In general, the specific operational
modes associated with helicopter flight would include:
(a)
Approach;
(b)
Take-off;
(c)
Passing by;
(d)
Idling;
(e)
Hovering;
(f)
Touch-down; and
(g)
Lift-off
3.58
Due to the extremely rapid
changes between each operational mode and the directivity of this particular
noise source, the modes of helicopter operation were combined into “six” modes
for assessment. These six modes are as
follows:
(a)
Approach = Approach
(b)
Hovering + Touch Down = Hovering to Landing
(c)
Idling = Idling;
(d)
Lift-off + Hovering = Hovering to
Take Off
(e)
Take-off = Take-off
(f)
Passing by = Passing by
Current
Operation Mode of Existing MFT Helipad
3.59
The existing helicopter noise
impacts at the identified assessment points (The Bauhinia, Ka On Building and
Talon Tower) for all modes of helicopter operation including approach,
hovering, idling, takeoff, were assessed in term of Lmax during daytime and;
Lmax and Leq (4 hours) during evening time period, making reference to the
existing flight frequency
and the type
of helicopter used, and the on site measurement noise data. The noise impacts arising from passing-by
was also assessed for the above three NSRs, in addition to NSRs at Hongway
Garden, Harmony Court and Sea View Mansion.
The assessment scenarios for existing MFT Helipad are summarised in Table 3.8.
Table 3.8 Assessment Scenarios for Existing MFT Helipad
Scenario
|
Existing
Helipad
|
|
Scenario
1a
|
S76C+
Approach/Hovering/Idling/Takeoff
(Flight
Path: Approach from the East and Takeoff to the West)
|
|
Scenario
1b
|
S76C+
Approach/Hovering/Idling/Takeoff
(Flight
Path: Approach from the West and Takeoff to the East)
|
|
Scenario
1c
|
S76C+
Passing-by along the flight path
|
Future
Operation Mode of Proposed MFT Helipad
3.60
The potential daytime and evening
time noise impacts arising from the proposed new helipad at the identified assessment
points were assessed based on the worse case scenarios (i.e. maximum capacity
of the helipad and allowable number of movements during evening period). The noise impacts arising from all modes
of helicopter operation including helicopter S76C+ and S92 were assessed. The worst case scenarios considered in the
assessment for daytime and evening time period, in terms of Lmax and Leq (4
hours), are summarised in Table 3.9.
Table 3.9 Assessment Scenarios for Proposed New MFT Helipad
Scenario
|
Proposed
new helipad
|
|
Scenario
2a
|
S76C+
Approach/Hovering/Idling/Takeoff (Flight Path: Approach from the East and
Takeoff to the West)
|
|
Scenario
2b
|
S76C+
Approach/Hovering/Idling/Takeoff
(Flight
Path: Approach from the West and Takeoff to the East)
|
|
Scenario
2c
|
S76C+
Passing-by along flight path
|
|
Scenario
2d
|
S92
Approach/Hovering/Idling/Take Off (Flight Path: Approach from the East and
Takeoff to the West)
|
|
Scenario
2e
|
S92
Approach/Hovering/Idling/Take Off (Flight Path: Approach from the West and
Takeoff to the East)
|
|
Scenario
2f
|
S92
Passing-by along flight path
|
Cumulative
Impact from Proposed New MFT Helipad & Existing Helipad
3.61
As informed by CAD, only one
helicopter will be allowed to land or hover or depart at any one time, with one
helicopter idling at the other helipad due to the flight safety requirement.
3.62
In this assessment, the
cumulative noise impacts generated from the operation of helicopters at the
proposed new helipad together with the existing one at MFT would be assessed
under the worst-case scenario. The
noise levels at the three representative NSRs including The Bauhinia, Ka On
Building and Talon Tower, in term of Lmax during daytime and; Lmax and Leq (4
hours) during evening time, would be calculated and the assessment scenarios
are presented in Table 3.10.
Table 3.10 Assessment
Scenarios for Cumulative Noise Impact from both Existing and Proposed MFT
Helipads
Scenario
|
Existing
Helipad
|
Proposed
new helipad
|
|
Scenario
3a
|
S76C+
Idling
|
S76C+
Approach / Hovering / Takeoff
(Fight
Path: Approach from the East and Takeoff to the West)
|
|
Scenario
3b
|
S76C+
Idling
|
S76C+
Approach / Hovering / Takeoff
(Fight
Path: Approach from the West and Takeoff to the East)
|
|
Scenario
3c
|
S76C+
Idling
|
S92
Approach / Hovering / Takeoff
(Fight
Path: Approach from the East and Takeoff to the West)
|
|
Scenario
3d
|
S76C+
Idling
|
S92
Approach / Hovering / Takeoff
(Fight
Path: Approach from the West and Takeoff to the East)
|
|
Scenario
4a
|
S76C+
Approach / Hovering / Takeoff
(Fight
Path: Approach from the East and Takeoff to the West)
|
S76C+
Idling
|
|
Scenario
4b
|
S76C+
Approach / Hovering / Takeoff
(Fight
Path: Approach from the West and Takeoff to the East)
|
S76C+
Idling
|
|
Scenario
4c
|
S76C+
Approach / Hovering / Takeoff
(Fight
Path: Approach from the East and Takeoff to the West)
|
S92
Idling
|
|
Scenario
4d
|
S76C+
Approach / Hovering / Takeoff
(Fight
Path: Approach from the West and Takeoff to the East)
|
S92
Idling
|
3.63
As the flight path has already
avoided noise sensitive land uses, no flyover zone restriction would need to be
considered in the assessment.
3.64
For determination of helicopter
noise impact to NSRs during 1900 to 2300 hours, the Lmax and Leq (4 hrs) at the
three assessed NSRs including the Bauhinia, Ka On Building and Talon Tower
would be calculated based on the maximum number of 22 movements of helicopter
S76C+ on the proposed new helipad during that period. Regarding the operation of S92 at the proposed new helipad, the
number of allowable helicopter
movements would be estimated so as to comply with the
proposed evening time noise limit.
3.65
Screening effect of the Shun Tak
Centre during different modes of operation such as hovering and idling modes
was taken into account for the noise assessment at the assessed NSRs. A plan, which demonstrate the screening
effect from the Shun Tak Centre on the NSRs are presented in Figure 3.6. Details for correction of screening effect is addressed in
Section 3.68.
Evaluation of Potential Impact
Construction Phase
3.66
The nearest NSR in the vicinity
of the construction site is the Bauhinia, which is located at 175m from the
work boundary of the proposed new helipad.
Shun Tak Centre, which is sited between the proposed new helipad and the
Bauhinia, would produce at least 5 dB(A) noise screening effect.
3.67
The predicted noise level at the
Bauhinia during construction works for proposed new helipad is presented in Table 3.11. Results indicated that the nearest NSRs to the work areas would
comply with the daytime construction noise criterion of 75 dB(A). It is expected that other NSRs located further
away from the work sites would also comply with the standard.
Table 3.11 Unmitigated
Construction Noise Levels at Representative NSR
|
NSR
|
Distance
between NSR and notional source position
|
Sound
Power Level dB(A)
|
Sound Pressure Level dB(A) #
|
|
The Bauhinia
|
175 m
|
117.7
|
62.8
|
Note:
# - attenuation of 5 dB(A) due to screening effect from Shun Tak Centre was
considered in the predicted noise levels.
Operation Phase
3.68
The predicted helicopter noise
levels at the assessed NSRs due to helicopters operating at the existing and proposed
new helipads
were calculated based on the measurement data of helicopter S76C+
operated at the existing helipad and the manufacturer data provided by the
current helicopter operator, taking into account distance correction and correction
from screening effect. As the proposed
new helipad is located behind Shun Tak Centre, the correction due to screening
effect for the three assessed NSRs applied in the assessment are summarised in Tables 3.12.
Table
3.12 Noise Correction due to
Screening Effect for Assessed NSRs when Helicopter Operating at the Proposed
new helipad
|
NSR
|
Approach
|
Hovering
|
Idling
|
Take Off
|
Remarks
|
|
Flight
Path: Approach from the East and Takeoff to the West
|
|
The
Bauhinia (N5)
|
No
correction due to screening effect
|
Totally screen by Shun Tak Centre; negative
correction of 10 dB(A)
|
Totally
screen by Shun Tak Centre; negative correction of 10 dB(A)
|
No
correction due to screening effect
|
Measurement
on Harbour Commercial Building which have direct line of sight to the existing
helipad during all modes of helicopter operations.
|
|
Ka
On Building (N6)
|
No
correction
|
Totally screen by Shun Tak Centre; negative
correction of 5 dB(A)
|
Totally
screen by Shun Tak Centre; negative correction of 5 dB(A)
|
No
correction
|
Ka
On Building could not view the whole process of approach (from the east),
hovering and idling mode of helicopter at existing helipad during measurement
due to partial screen from Shun Tak Centre ; no correction for approach mode
and negative correction of 5 dB(A) for hovering & idling in the
calculation.
|
|
Talon
Tower (N6a)
|
No
correction due to screening effect
|
No
correction due to screening effect
|
No
correction due to screening effect
|
No
correction due to screening effect
|
-
|
|
Flight
Path: Approach from the West and Takeoff to the East
|
|
The
Bauhinia (N5)
|
No
correction due to screening effect
|
Totally
screen by Shun Tak Centre; negative correction of 10 dB(A)
|
Totally
screen by Shun Tak Centre; negative correction of 10 dB(A)
|
No
correction due to screening effect
|
Measurement
on Harbour Commercial Building which have direct line of sight to the
existing helipad during all modes of helicopter operations.
|
|
Ka
On Building (N6)
|
No
correction due to screening effect
|
Totally
screen by Shun Tak Centre; negative correction of 5 dB(A)
|
Totally
screen by Shun Tak Centre; negative correction of 5 dB(A)
|
No
correction
|
Ka On Building could not view the
whole process of idling, hovering and take off (to the East) due to partial
screen by Shun Tak Centre during measurement, no correction for measured
noise level for take off mode and negative correction of 5 dB(A) for hovering
& idling in the calculation.
|
|
Talon
Tower (N6a)
|
No
correction due to screening effect
|
No
correction due to screening effect
|
No
correction due to screening effect
|
No
correction due to screening effect
|
-
|
3.69
Detailed assessment results for
all studied scenarios are presented in Appendices
3.6 and 3.7. The predicted noise levels Lmax during 0800
– 2300 hours and Leq (4 hours) during 1900 – 2300 hours at the assessed NSRs for
existing operation mode and future operation mode are described as following
paragraphs. The predicted noise levels
arising from the proposed new helipad and both existing and proposed new
helipads were compared against the daytime helicopter noise criteria of Lmax 85
dB(A) under the EIAO-TM and proposed evening time (1900 – 2300 hours) noise
limits of Leq (4 hours) 65 dB(A) and Lmax 85 dB(A).
Current
Operation Mode of Existing MFT Helipad
3.70
Based on the measurement results
with appropriate distance correction, the noise levels Lmax at representative
assessment points during 0800 to 2300 hours would be 75 – 86 dB(A). The noise levels Leq (4 hours) at the
representative assessment points during 1900 – 2300 hours would be 63 – 68
dB(A) based on the existing flight frequency and 64 – 69 dB(A) based on
current allowable condition. The
results are summarised in Tables 3.13
and 3.14 respectively. Detailed calculations are presented in Appendices 3.6 and 3.7.
Table
3.13 Predicted Noise Levels, Lmax,
during 0800-2300 hours for Existing Operation Mode
Scenario
|
Noise Source
|
Predicted Noise Level, Lmax
dB(A)*
|
|
The Bauhinia
|
Ka On Building
|
Talon Tower
|
Hongway Garden
|
Harmony Court
|
Sea View Mansion
|
|
1a
|
S76C+ at Existing Helipad (Approach from East)
|
84 (Hovering
to landing)*
|
82
(Take off)*
|
82 (Hovering to landing)*
|
-
|
-
|
-
|
|
1b
|
S76C+ at Existing Helipad (Approach from West)
|
84 (Hovering
to takeoff )*
|
86 (Hovering
to landing)*
|
84 (Hovering to landing)*
|
-
|
-
|
-
|
|
1c
|
S76C+ Passing-by
|
80
|
83
|
83
|
82
|
80
|
80
|
Note: * Worst
case scenario
Table
3.14 Predicted Noise Levels, Leq (4
hours), during 1900-2300 hours for Existing Operation Mode (based on Current
and Maximum Allowable Number of Movement)
Flight Path
|
Predicted Noise Level, Leq(4hours) dB(A)
|
The Bauhinia
|
Ka
On Building
|
Talon Tower
|
|
S76C+ operated at existing helipad (16 movements during 1900 - 2259)
|
|
|
66
|
63
|
65
|
|
|
67
|
68
|
65
|
|
S76C+ operated at existing helipad (22 movements during 1900 - 2259)
|
|
|
68
|
64
|
66
|
|
|
69
|
69
|
67
|
Future
Operation Mode of Proposed New MFT Helipad
3.71
Assessment results indicated that
the noise levels Lmax at representative assessment points during 0800 to 2300
hours due to operation (different modes of operation and flight directions) of
helicopter S76C+ would be 67 – 85 dB(A) (see Appendix 3.6). The predicted noise levels Leq (4 hours) at
the representative assessment points during 1900 – 2300 hours would be 61 – 65
dB(A). Therefore, the operation of
helicopter S76C+ or the helicopter with its noise emission level less than
helicopter S76C+, such as AB 139, at the proposed new helipad would comply with
the assessment criteria. If no noise
exceedance of daytime noise criterion and proposed evening time noise criteria
is found at these six representative assessment points due to the proposed new
helipad operation, other NSRs located at the coastal area within 300m of the
Project boundary and along the flight paths in the Western District would also
comply with the criteria. The predicted noise levels for each scenario are
summarised in Table 3.15 and Table 3.16. Detailed assessment results are presented in Appendices 3.6 and 3.7.
3.72
Regarding the operation of
helicopter S92 at the proposed new helipad, the predicted noise level Lmax at the
representative assessment points during 0800 to 2300 hours would be 70 – 86
dB(A). The predicted noise levels Leq
(4 hours) at the representative assessment points during 1900 – 2300 hours
would be 62 – 67 dB(A). Results
indicated that the predicted noise levels at NSRs would not comply with the
daytime noise criteria of Lmax stipulated in the EIAO-TM and evening time
assessment criteria when helicopter S92 approaching from the west, therefore, helicopter S92 was recommended not to be
operated at the proposed new helipad preventing excessive noise impacts to the
nearest NSRs in vicinity of the helipad.
The result table for helicopter S92 is presented in Appendix 3.8.
3.73
The noise contour (refer to Figures 3.7), in terms of Lmax, would
be provided for the Scenario 2a/2b (S76C+ operating (hovering to take off) on
the proposed new
helipad at MFT Building) which would be the
highest predicted noise levels when the helicopter operating at the proposed new
helipad only.
Table
3.15 Predicted Noise Levels, Lmax,
during 0800-2300 hours for Future Operation Mode of Proposed New MFT Helipad
Scenario
|
Noise Source
|
Predicted Noise Level, Lmax
dB(A)*
|
|
The Bauhinia
|
Ka On Building
|
Talon Tower
|
Hongway Garden
|
Harmony Court
|
Sea View Mansion
|
|
2a
|
S76C+ at Proposed new helipad (Approach
from East)
|
83 (Takeoff)*
|
80 (Takeoff)*
|
81 (Hovering
to landing)*
|
-
|
-
|
-
|
|
2b
|
S76C+ at Proposed new helipad (Approach
from West)
|
85
(Takeoff)*
|
83 (Approach)*
|
82 (Hovering to landing*
|
-
|
-
|
-
|
|
2c
|
S76C+ Passing-by
|
80
|
83
|
83
|
82
|
80
|
80
|
Note: *
Worst case scenario
Table
3.16 Predicted Noise Levels, Leq (4
hours), during 1900-2300 hours for Future Operation Mode of Proposed new
helipad
Flight Path
|
Predicted Noise Level, Leq(4hours) dB(A)
|
The Bauhinia
|
Ka
On Building
|
Talon Tower
|
|
S76C+ operated at proposed new helipad (22 movements during 1900 – 2259)
|
|
|
64
|
61
|
65
|
|
Approach from the
West and Takeoff to the East
|
65
|
65
|
65
|
Cumulative
Impact from Existing Helipad & New Helipad at MFT
3.74
The
predicted maximum noise levels, Lmax, at representative assessment points due
to cumulative noise impacts from helicopter S76C+ operation at the existing and
new helipads are summarised in Table 3.17. The assessment results show that the Lmax 85 dB(A) criteria
(daytime and evening time) would be met, except a slight noise exceedance at Ka
On Building in Scenario 4b (S76C+ hovering to landing at the existing helipad
and S76C+ idling at proposed new helipad), due to helicopter noise from the
operation at the existing helipad as previously shown in Table 3.13. Detailed assessment results are presented in
Appendices 3.6 and 3.7.
3.75
Regarding
the cumulative helicopter noise impact during evening time, the maximum
allowable number of helicopter movements at
the existing and new helipads was assessed so as to comply with the
following conditions.
(i)
The
noise level from helicopter S76C+ operation at the new helipad would not exceed
the criterion of Leq (4 hour) 65 dB(A);
and
(ii)
The
cumulative noise levels from the existing and new helipads at the individual
NSRs would not be worse than the existing allowable helipad operation
conditions (22 movements during 1900 – 2259 hours) by 1.0 dB(A).
3.76
The
predicted maximum noise levels, Leq (4 hours) during
1900 – 2300 hours, at
representative assessment points due to cumulative noise impacts from
helicopter S76C+ operation at both existing and new helipads are presented in Appendix 3.9, demonstrating different combinations of flight
schedule at the existing and new helipads which would comply with the two
conditions stipulated in Section 3.75.
3.77
The noise contours (refer to Figures
3.8), in terms of Lmax, are provided for the Scenario 3a/3b (S76C+ hovering
on the proposed new helipad and S76C+ Idling on the existing helipad at MFT
Building), which would be the highest predicted noise levels
in the cumulative scenarios.